1. Field of the Invention
The present invention relates to a fluid saving type fluid feed nozzle, a fluid saving type treatment fluid feed nozzle apparatus, a washing treatment system, and a treatment apparatus used for a wet treatment or a dry treatment such as washing, etching, development or stripping.
2. Description of the Related Art
From the point of view of washing from among the surface fluid treatments of large-sized substrates such as a substrate for solar cell, a substrate for liquid crystal, a substrate for plastic package and the like, the conventional art and problems will be described below.
A washing apparatus shown in FIG. 52 has conventionally been commonly used. FIG. 52A is a side view, and FIG. 52B is a plan view.
Washing is carried out by feeding a washing liquid such as extra-pure water, electrolytic in water, ozone water or hydrogen water by means of a wet treatment liquid feed nozzle 2 onto the upper surface of a substrate 1 while moving the substrate 1, for example, in the arrow A direction.
A washing liquid feed chamber 4, an opening section 6 guiding the washing liquid onto the substrate and a washing liquid introducing port 7 for introducing the washing liquid into the washing liquid feed chamber 4 are formed, as shown in FIG. 53 in this wet treatment liquid feed nozzle 2.
An ultrasonic element 16 is provided above the washing liquid feed chamber 4 to improve washing effect by imparting an ultrasonic wave of the order of MHz band to the washing liquid.
A washing liquid such as extra-pure water, electrolytic ion water, ozone water or hydrogen water is introduced from a washing liquid introducing port 7 into the washing liquid feed chamber 4 and fed to the substrate surface which is an object to be washed through the opening section 6 to wash the same. After washing with the washing liquid, rinsing is performed with a rinsing liquid (extra-pure water in general) by means of a nozzle having a structure similar to that of the wet treatment liquid feed nozzle 2 shown in FIG. 53 with a view to removing the washing liquid from the surface of the object to be washed, and to eliminating residual particles and the like.
However, the aforesaid conventional art has the following problems.
(1) First, it requires a large consumption of a washing liquid or a rinsing liquid.
For example, in order to achieve a cleanliness as represented by a amount of residual particles (for example, Al.sub.2 O.sub.3 particles) remaining on the substrate 1 on a level of 0.5 particles/cm.sup.2, when a 500 mm square substrate 1 is washed with a washing liquid such as electrolytic ion water, and then rinsed with a rinsing liquid, the washing liquid and the rinsing liquid must be fed at a flow rate within a range of from about 25 to 30 L/min. The flow rate within a range of from 25 to 30 L/min is selected to permit imparting a stable ultrasonic wave. With a rate of under 25 to 30 L/min, therefore, it becomes impossible to stably impart an ultrasonic wave, and hence to wash cleanly. The consumption of the washing liquid must currently be large for the reason as described above. A liquid consumption of 25 to 30 L/min is still required because the frequency of the ultrasonic wave is raised and the nozzle slit width of ultrasonic washing is reduced. Here is a limit of the existing art.
(2) The second problem is that applicability of ultrasonic wave near the MHz band is limited. There is currently available ultrasonic wave within a range of from 0.7 to 1.5 MHz. In all cases of wet treatment, occurrence of a damage to the object to be treated should be avoided. For this purpose, it is the usual practice to use ultrasonic wave near the MHz band which does not cause a damage resulting from cavitation in washing. A lower limit of usage is adopted from the point of view of avoiding occurrence of a damage to the object to be treated. An upper limit is selected in view of the fact that an effective power available for washing cannot be derived with ultrasonic wave of a frequency of over 2 MHz. Conceivable reasons of impossibility to derive an effective power applicable for washing include the facts that the effective power is low because of a problem in circuit of the ultrasonic element and that, as shown in FIG. 53, the ultrasonic element is distant from the object to be wet-treated, resulting in a large attenuation of ultrasonic power.
(3) The third problem is that, because the washing liquid imparted with an ultrasonic wave as in the washing liquid feed chamber 4 is fed via the narrow opening section 6 onto the object to be washed, there occurs a considerable damping of ultrasonic output, this leading to the necessity to increase the input power beyond necessity and therefore to a shorter service life of the ultrasonic oscillator. With an ultrasonic wave having a frequency within a range of from 0.7 to 1.5 MHz, while it is possible to derive an effective power applicable for washing, the ultrasonic element is distant from the object to be washed as shown in FIG. 53, and damping of the ultrasonic power is still serious. Load on the adhering surface of the ultrasonic oscillator is very large so that only a slight change in the feed amount of washing liquid or the like may often cause a failure.
(4) The fourth problem lies in cleanliness after washing. Even when a large amount of washing liquid (25 to 30 L/min) is used and a sufficient rinsing is carried out after washing as described above, the resultant cleanliness is limited to a level, resulting in an average cleanliness of about 0.5 particles/cm.sup.2.
When a higher cleanliness (about 0.05 particles/cm.sup.2) is demanded, the conventional washing technology cannot cope with this demand. Even within a substrate, furthermore, there are fluctuations of cleanliness, and therefore, the portion on the side (b) opposite to the travel of the substrate 1 as shown in FIG. 52 shows a cleanliness lower than that of the portion (a) on the travelling side. As is clear from the distribution of cleanliness shown in FIG. 52B, a problem is that the portion closer to the leading end (a) in the travelling direction has a higher cleanliness, and cleanliness worsens toward the rear end (b) in the travelling direction.
This is attributable to the fact that particles once removed adhere again to the substrate surface while the washing liquid fed from the feed nozzle to the substrate surface flows in the form of a liquid film on the surface of the large-sized substrate to the substrate edge.
The present inventors obtained the following findings regarding washing, a form of wet treatment. Consideration on reasons why a high cleanliness could not be obtained from washing by means of a conventional washing apparatus as shown in FIG. 50 led to a conclusion that it was caused by the following reasons. When the washing liquid is fed from the nozzle opening section 6, the leading end side (a) of the substrate 1 is washed. However, since the substrate 1 travels in the arrow A direction, the washing liquid having washed the surface is transferred smoothly along the surface of the substrate 1 to the rear end (b) of the substrate 1. Because the washing liquid after washing contains particles, these particles adhere again to the surface of the substrate 1 during travel toward the (b) end side. The amount of accumulated particles is larger in the washing liquid after washing at a position closer to the rear end so that the amount of adhesion is larger, leading to a poorer cleanliness.
The present inventors thus clarified that the cause of a poorer cleanliness and an increased consumption of rinsing liquid lay in re-adhesion of once removed particles.
The present invention is therefore to prevent, in a wet treatment method for gradually feeding a wet treatment liquid to an object to be wet-treated, re-adhesion of a wet treatment liquid fed from the wet treatment liquid feed nozzle to the object to be wet-treated, by removing the same from the object to be wet-treated without allowing it to come substantially into contact with portions other than the portion to which the wet treatment liquid has been fed. More particularly, re-adhesion is prevented by immediately removing the wet treatment liquid having contributed to a wet treatment to outside the system.
The present inventors developed a wet treatment liquid feed nozzle, a wet treatment apparatus and a wet treatment method as described above as a technique for preventing re-adhesion.
The invention has therefore an object to provide a liquid-saving type treatment liquid feed nozzle, a treatment liquid feed nozzle apparatus, a washing system and a treatment apparatus which solve the problems of the conventional wet and dry treatment apparatuses and wet and dry treatment methods, permit reduction of the consumption of the treatment liquid to under a tenth the conventional consumption, and allow to obtain a higher cleanliness than the conventional one.
Another object of the invention is to provide a treatment liquid feed nozzle, a treatment liquid feed nozzle apparatus and a treatment apparatus in which leakage of the treatment liquid from the treated surface of the object to be treated to outside is non-existent or very slight, if any.